Obesity and the multitude of co-morbidities associated with obesity such as diabetes, dyslipidemia, coronary heart disease, and certain cancers are a major concern for public health. The currently available pharmaceutical therapies for the treatment of obesity have limited efficacy and side effects that limit their use. Thus, there is a significant medical need for better pharmacotherapy for obesity.
Melanin-concentrating hormone (MCH) has been identified as an orexigenic peptide that exerts an effect on food intake and body weight regulation. MCH is a cyclic 19 amino acid neuropeptide expressed in the zona incerta and lateral hypothalamus in response to both energy restriction and leptin deficiency. MCH is known to stimulate feeding when injected into the lateral ventricle of rats and the mRNA for MCH is upregulated in the hypothalamus of genetically obese mice (ob/ob) and in fasted control and ob/ob animals. In addition, animals treated with MCH show increases in glucose, insulin and leptin levels, mimicking human metabolic syndrome (Gomori, A. Chronic infusion of MCH causes obesity in mice Am. J. Physiol. Endocrinol. Metab. 284, E583, 2002). Mice lacking MCH are hypophagic and lean with increased metabolic rate, whereas animals over-expressing MCH gain excess weight on both standard and high fat diets. MCH is thought to have effects on other nervous system functions as well (Rocksz, L. L. Biological Examination of Melanin Concentrating Hormone 1: Multi-tasking from the hypothalamus Drug News Perspect 19(5), 273, 2006). An orphan G-protein coupled receptor (GPCR) was recently identified as a receptor for MCH. Disruption of the binding between MCH and the MCH receptor, i.e. MCH antagonism, may thus be used to counteract the effects of MCH (McBriar, M. D. Recent advances in the discovery of melanin-concentrating hormone receptor antagonists Curr. Opin. Drug Disc. & Dev. 9(4), 496, 2006).